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This compact, Creative-Commons-licensed ultra-SAXS module, augments existing high-performance SAXS/WAXS synchrotron instruments, so that larger structures may be measured. Its functionality is demonstrated at the I22 beamline at Diamond Light Source, where the combined USAXS/SAXS/WAXS range of an alumina membrane, a porous carbon catalyst and silica, covers over four decades in scattering angle., Ultra-SAXS can enhance the capabilities of existing synchrotron SAXS/WAXS beamlines. A compact ultra-SAXS module has been developed, which extends the measurable q-range with 0.0015 ≤ q (nm−1) ≤ 0.2, allowing structural dimensions in the range 30 ≤ D (nm) ≤ 4000 to be probed in addition to the range covered by a high-end SAXS/WAXS instrument. By shifting the module components in and out on their respective motor stages, SAXS/WAXS measurements can be easily and rapidly interleaved with USAXS measurements. The use of vertical crystal rotation axes (horizontal diffraction) greatly simplifies the construction, at minimal cost to efficiency. In this paper, the design considerations, realization and synchrotron findings are presented. Measurements of silica spheres, an alumina membrane, and a porous carbon catalyst are provided as application examples.

An important and integral effort toward understanding the formation and reorganization of mesoscale structures in functional organic thin films, being of fundamental importance to the development o...

International audience; We investigate the damage mechanisms of amorphous and low semi-crystalline semi-aromatic polyamides, polyphthalamides (PPA) and two other amorphous polymers, polycarbonate (PC) and poly(metyl)methacrylate (PMMA) under tensile deformation. Ultra-Small Angles X-ray Scattering (USAXS) experiments permit to describe the beginning of the damage and the growth of crazes. Interpreting the results allows to measure the volume fractions of damages, as well as their distribution of sizes at different stages of tensile deformation. Different modes of damage are observed. They are initiated by the nucleation of nanometric crazes around pre-existing defects for PC, PMMA and the amorphous polyamide. Then the growth of these crazes is blocked by the strain hardening at the local level. By increasing the strain further, the growth of a second family of large crazes is observed for these three polymers before the yielding which leads to fracture for PC and PMMA far in the macroscopic strain hardening regime, but not for the amorphous polyamide for which damaged is stabilized after the stress softening and in the ensuing necking regime for which strain hardening is also observed. In the case of two low semi-crystalline polyamides, no damage is observed at all and deformation takes place by necking without damaging and breaking. We propose interpretations for these different behaviors.

In the last few years, a new class of polyamides has been developed for specific applications requiring better mechanical and thermal properties, such as electronics or automotive industry. Polyphthalamides (PPA) are semi-aromatic polyamides containing aromatic rings in their main chain. Recently, the damage mechanisms have been studied in the case of semi-crystalline (PA66) and amorphous (cellulose acetate) polymers. The aim of the PhD thesis was to study the damage mechanisms of amorphous and semi-crystalline polymers. In addition, few studies have been conducted to characterize the properties of pure PPA. More detailed data regarding their mechanical properties are needed. The study of the properties of this class of polymers is important, especially since their applications are different from aliphatic polyamides. We first characterized these polymers and then studied their mechanical behavior in traction, compression and Charpy impact strength. We have thus been able to highlight the appearance of a necking phenomenon and a strain hardening regime from 20% deformation for three PPA studied. Strain hardening has also been observed in other amorphous ductile polymers such as polycarbonate (PC) or poly(methyl methacrylate) (PMMA). The strain hardening stabilizes the deformation by avoiding the localization of the damage. In order to describe the microscopic mechanisms associated with the initiation and propagation of damage under tensile deformation of our polymers, we have carried out observations by scanning transmission electron microscopy (STEM) and optical microscopy as well as by Ultra-small angle X-ray scattering (USAXS). The analysis of these different polymers (amorphous and semi-crystalline PPA, PC, PMMA) by USAXS highlights different modes of damage. The simultaneous nucleation of nanometric crazes around the pre-existing defects (defects related to the injection process), then the limited growth of these crazes are observed for the amorphous PPA, the PC and the PMMA studied, in a mechanism similar to that studied in the case of cellulose acetate. The damage is blocked in the first place by the strain hardening. However, in the case of polycarbonate and PMMA, when the stress applied becomes sufficiently high, a small fraction of these crazes grows faster to cause the rupture of the sample, which allows to observe the evolution of a second family of larger crazes. We also observe the growth of a second family of crazes for one of the amorphous PPA, but their growth stops at the appearance of necking. No failure of the sample is observed. The second amorphous PPA is damaged by cavitation up to about 5% deformation. The cavities stop to grow at the appearance of shear bands. When the shear bands propagated on either side of the sample, the failure is observed. The two semi-crystalline PPA deform by necking without failure. No cavitation was observed by USAXS. The damage of the polymers studied can be classified into three categories. The first category concerns polymers that behave similarly to cellulose acetate. Crazing nucleation is observed, which growth is initially blocked by strain hardening. When the stress applied becomes sufficiently high, a fraction of these crazes increases more rapidly until the sample is broken, which makes it possible to observe the evolution of a second family of larger crazes. This category concerns polycarbonate and PMMA. The second category concerns one of the amorphous PPA with crazes whose growth is initially blocked also by strain hardening. The growth of a second family of crazes stops at the appearance of necking, and no failure of the specimen is observed. The last category concerns polymers that do not show any damage. These are the two semi-crystalline PPA. We propose in this thesis an interpretation of these different mechanisms of damage; Ces dernières années, une nouvelle classe de polyamides a été développée pour des applications spécifiques nécessitant de meilleures propriétés mécaniques et thermiques, telles que l’électronique ou l’industrie automobile. Les polyphtalamides (PPA) sont des polyamides semi-aromatiques, contenant des cycles aromatiques dans leur chaine principale. Récemment, les mécanismes d’endommagement ont été étudiés dans le cas de polymères semi-cristallins (PA66) et amorphes (acétate de cellulose). Le but de la thèse a été d’étudié les mécanismes d’endommagement de polymères amorphes et semi-cristallins. Par ailleurs, peu d'études ont été réalisées pour caractériser les propriétés des PPA purs. Des données plus détaillées concernant leurs propriétés mécaniques sont nécessaires. L'étude des propriétés de cette classe de polymères est importante, d'autant plus que leurs applications sont différentes des polyamides aliphatiques. Nous avons dans un premier temps caractérisé ces polymères puis étudié leur comportement mécanique en traction, compression et choc. Nous avons ainsi pu mettre en évidence l’apparition d’un phénomène de striction et d’un régime de durcissement plastique (strain hardening) dès 20% de déformation pour trois PPA étudiés. Le durcissement plastique a également été observé dans d’autres polymères amorphes ductiles tels que le polycarbonate (PC) ou le poly(méthyle methacrylate) (PMMA). Afin de décrire les mécanismes microscopiques liés à l’initiation et la propagation de l’endommagement sous traction de nos polymères, nous avons réalisé des observations par microscopie électronique à balayage en transmission (STEM) et microscopie optique ainsi que par diffusion des rayons X aux très petits angles (USAXS). L’analyse de ces différents polymères (PPA amorphes et semi-cristallins, PC, PMMA) par USAXS met en évidence différents modes d’endommagement. La nucléation simultanée de craquelures nanométriques autour des défauts préexistants (défauts liés au processus d’injection), puis la croissance limitée de ces craquelures sont observées pour les PPA amorphes, le PC et le PMMA étudiés, dans un mécanisme similaire à celui étudié dans le cas de l’acétate de cellulose. L’endommagement est bloqué dans un premier temps par le durcissement plastique. Dans le cas du polycarbonate et du PMMA, lorsque la contrainte appliquée devient suffisamment élevée, une petite fraction de ces craquelures croît plus rapidement jusqu’à entrainer la rupture de l’échantillon, ce qui permet d’observer l’évolution d’une deuxième famille de craquelures de plus grandes tailles. On observe également la croissance d’une deuxième famille de craquelures pour l’un des PPA amorphe, mais leur croissance s’arrête à l’apparition de la striction. Aucune rupture n’est observée. Les deux PPA semi-cristallins se déforment par striction sans rupture. Aucune cavitation n’a été observée par USAXS. L’endommagement des polymères étudiés se classe en trois catégories. La première catégorie concerne les polymères qui ont un comportement similaire à l’acétate de cellulose. On observe la nucléation de craquelures dont la croissance est dans un premier temps bloquée par le durcissement plastique. Lorsque la contrainte appliquée devient suffisamment élevée une fraction de ces craquelures croît plus rapidement jusqu’à entrainer la rupture de l’échantillon, ce qui permet d’observer l’évolution d’une deuxième famille de craquelures de plus grandes tailles. Cette catégorie concerne le polycarbonate et le PMMA. La deuxième catégorie concerne l’un des PPA amorphe ayant des craquelures dont la croissance est dans un premier temps bloquée par le durcissement plastique. La croissance d’une deuxième famille de craquelures s’arrête à l’apparition de la striction, et aucune rupture n’est observée. La dernière catégorie concerne les polymères ne présentant pas d’endommagement (PPA semi-cristallins). Nous proposons dans cette thèse une interprétation de ces différents mécanismes d’endommagement.

In the last few years, a new class of polyamides has been developed for specific applications requiring better mechanical and thermal properties, such as electronics or automotive industry. Polyphthalamides (PPA) are semi-aromatic polyamides containing aromatic rings in their main chain. Recently, the damage mechanisms have been studied in the case of semi-crystalline (PA66) and amorphous (cellulose acetate) polymers. The aim of the PhD thesis was to study the damage mechanisms of amorphous and semi-crystalline polymers. In addition, few studies have been conducted to characterize the properties of pure PPA. More detailed data regarding their mechanical properties are needed. The study of the properties of this class of polymers is important, especially since their applications are different from aliphatic polyamides. We first characterized these polymers and then studied their mechanical behavior in traction, compression and Charpy impact strength. We have thus been able to highlight the appearance of a necking phenomenon and a strain hardening regime from 20% deformation for three PPA studied. Strain hardening has also been observed in other amorphous ductile polymers such as polycarbonate (PC) or poly(methyl methacrylate) (PMMA). The strain hardening stabilizes the deformation by avoiding the localization of the damage. In order to describe the microscopic mechanisms associated with the initiation and propagation of damage under tensile deformation of our polymers, we have carried out observations by scanning transmission electron microscopy (STEM) and optical microscopy as well as by Ultra-small angle X-ray scattering (USAXS). The analysis of these different polymers (amorphous and semi-crystalline PPA, PC, PMMA) by USAXS highlights different modes of damage. The simultaneous nucleation of nanometric crazes around the pre-existing defects (defects related to the injection process), then the limited growth of these crazes are observed for the amorphous PPA, the PC and the PMMA studied, in a mechanism similar to that studied in the case of cellulose acetate. The damage is blocked in the first place by the strain hardening. However, in the case of polycarbonate and PMMA, when the stress applied becomes sufficiently high, a small fraction of these crazes grows faster to cause the rupture of the sample, which allows to observe the evolution of a second family of larger crazes. We also observe the growth of a second family of crazes for one of the amorphous PPA, but their growth stops at the appearance of necking. No failure of the sample is observed. The second amorphous PPA is damaged by cavitation up to about 5% deformation. The cavities stop to grow at the appearance of shear bands. When the shear bands propagated on either side of the sample, the failure is observed. The two semi-crystalline PPA deform by necking without failure. No cavitation was observed by USAXS. The damage of the polymers studied can be classified into three categories. The first category concerns polymers that behave similarly to cellulose acetate. Crazing nucleation is observed, which growth is initially blocked by strain hardening. When the stress applied becomes sufficiently high, a fraction of these crazes increases more rapidly until the sample is broken, which makes it possible to observe the evolution of a second family of larger crazes. This category concerns polycarbonate and PMMA. The second category concerns one of the amorphous PPA with crazes whose growth is initially blocked also by strain hardening. The growth of a second family of crazes stops at the appearance of necking, and no failure of the specimen is observed. The last category concerns polymers that do not show any damage. These are the two semi-crystalline PPA. We propose in this thesis an interpretation of these different mechanisms of damage, Ces dernières années, une nouvelle classe de polyamides a été développée pour des applications spécifiques nécessitant de meilleures propriétés mécaniques et thermiques, telles que l’électronique ou l’industrie automobile. Les polyphtalamides (PPA) sont des polyamides semi-aromatiques, contenant des cycles aromatiques dans leur chaine principale. Récemment, les mécanismes d’endommagement ont été étudiés dans le cas de polymères semi-cristallins (PA66) et amorphes (acétate de cellulose). Le but de la thèse a été d’étudié les mécanismes d’endommagement de polymères amorphes et semi-cristallins. Par ailleurs, peu d'études ont été réalisées pour caractériser les propriétés des PPA purs. Des données plus détaillées concernant leurs propriétés mécaniques sont nécessaires. L'étude des propriétés de cette classe de polymères est importante, d'autant plus que leurs applications sont différentes des polyamides aliphatiques. Nous avons dans un premier temps caractérisé ces polymères puis étudié leur comportement mécanique en traction, compression et choc. Nous avons ainsi pu mettre en évidence l’apparition d’un phénomène de striction et d’un régime de durcissement plastique (strain hardening) dès 20% de déformation pour trois PPA étudiés. Le durcissement plastique a également été observé dans d’autres polymères amorphes ductiles tels que le polycarbonate (PC) ou le poly(méthyle methacrylate) (PMMA). Afin de décrire les mécanismes microscopiques liés à l’initiation et la propagation de l’endommagement sous traction de nos polymères, nous avons réalisé des observations par microscopie électronique à balayage en transmission (STEM) et microscopie optique ainsi que par diffusion des rayons X aux très petits angles (USAXS). L’analyse de ces différents polymères (PPA amorphes et semi-cristallins, PC, PMMA) par USAXS met en évidence différents modes d’endommagement. La nucléation simultanée de craquelures nanométriques autour des défauts préexistants (défauts liés au processus d’injection), puis la croissance limitée de ces craquelures sont observées pour les PPA amorphes, le PC et le PMMA étudiés, dans un mécanisme similaire à celui étudié dans le cas de l’acétate de cellulose. L’endommagement est bloqué dans un premier temps par le durcissement plastique. Dans le cas du polycarbonate et du PMMA, lorsque la contrainte appliquée devient suffisamment élevée, une petite fraction de ces craquelures croît plus rapidement jusqu’à entrainer la rupture de l’échantillon, ce qui permet d’observer l’évolution d’une deuxième famille de craquelures de plus grandes tailles. On observe également la croissance d’une deuxième famille de craquelures pour l’un des PPA amorphe, mais leur croissance s’arrête à l’apparition de la striction. Aucune rupture n’est observée. Les deux PPA semi-cristallins se déforment par striction sans rupture. Aucune cavitation n’a été observée par USAXS. L’endommagement des polymères étudiés se classe en trois catégories. La première catégorie concerne les polymères qui ont un comportement similaire à l’acétate de cellulose. On observe la nucléation de craquelures dont la croissance est dans un premier temps bloquée par le durcissement plastique. Lorsque la contrainte appliquée devient suffisamment élevée une fraction de ces craquelures croît plus rapidement jusqu’à entrainer la rupture de l’échantillon, ce qui permet d’observer l’évolution d’une deuxième famille de craquelures de plus grandes tailles. Cette catégorie concerne le polycarbonate et le PMMA. La deuxième catégorie concerne l’un des PPA amorphe ayant des craquelures dont la croissance est dans un premier temps bloquée par le durcissement plastique. La croissance d’une deuxième famille de craquelures s’arrête à l’apparition de la striction, et aucune rupture n’est observée. La dernière catégorie concerne les polymères ne présentant pas d’endommagement (PPA semi-cristallins). Nous proposons dans cette thèse une interprétation de ces différents mécanismes d’endommagement.

Cellulose acetate (CA) is a bio based polymer. Melt processing of cellulose based thermoplastic polymers is a real challenge. One problem is the existence of a narrow window between the melting point and the degradation temperatures for cellulose acetate with a substitution degree (DS) around 2.45 (which is developed and commercialized by Rhodia Acetow). As a consequence, its processing can only be considered with a sufficient amount of externalplasticizer (between 15 and 30% by weight). The corresponding polymer/plasticizer blends areamorphous and their mechanical properties are mainly governed by the presence of a high volume fraction of strong hydrogen bonds. The plasticization of cellulose acetate has been thesubject of many studies allowing us to focus on two plasticizers: triacetin (TA), an eco-friendlyplasticizer frequently used for cellulose acetate and diethyl phthalate (DEP) which is the historicplasticizer of cellulose acetate which constitutes a reference for this work as it is usually the case in the literature. Few studies have been published regarding the mechanical properties of bulk cellulose acetate (prepared via injection molding). It is described that they are comparable to those of PS or poly(methyl methacrylate) (PMMA) and have proven to be particularly interesting. Cellulose acetate based materials usually display a high Young modulus. But its small deformation at break limits its potential for new applications. The objectives of this thesis are to deeply understand the mechanical properties and damage mechanisms of bulk plasticized cellulose acetate polymers. For this purpose we first analyzed the tensile behavior and the influence of various parameters such as nature and content of the plasticizer, but also the influence of the injection process. We have thus been able to highlight the appearance of a strain hardening regime from 8% of deformation under certain conditions. It appears that the choice of the plasticizer, the temperature of the experiment and the macroscopic pre-orientation of the chains significantly influence this regime. Strain hardening has already been observed in other amorphous polymers such as polycarbonate (PC) or poly (methyl methacrylate) (PMMA) which are classified as amorphous polymers called "ductile". The origin of this regime is still undeveloped and much debated, however it appears that it stabilizes the deformation by avoiding the localization of damage and is therefore a key parameter for improving the ductility of these polymers. In order to better understand this ductility, we have made some analysis by Scanning Transmission Electron Microscopy (STEM) as well as Ultra Small Angles X-ray Scattering (USAXS). Thanks to these characterizations we have been able to describe the micromechanisms of damage from macro to nano-scales and thus precisely describe the micromechanisms related to initiation and propagation of damage. By these analyzes we highlight the simultaneous nucleation of nano crazes around pre-existing defects (related to the injection process). These crazes grow slowly until reaching the hundred microns. However, when the applied stress becomes sufficiently high, a small portion of these crazes starts to grow faster until the failure of the sample. With DEP the kinetics of growth is very fast, causing a brittle failure of the sample. With TA this growth is slower, which makes it possible to observe the evolution of the larger crazes. This work proposes a new mechanism of damage in plasticized cellulose acetate based on experimental results and physical interpretations; L'acétate de cellulose (CA) est un bio-polymère issu de la cellulose du bois. Sa température de dégradation (dont le degré de substitution 2,5 est développé et commercialisé par le Groupe Solvay) étant très proche de sa température de fusion, son procédé de mise en oeuvre par voie fondue ne peut être envisagé qu'avec l'ajout d'une quantité importante de plastifiant externe (entre 15 et 30% en poids). Le polymère plastifié obtenu est classé parmi les thermoplastiques amorphes et ses propriétés sont régies par un «réseau» de très fortes interactions polaires. La plastification de l'acétate de cellulose à fait l'objet de nombreux travaux nous permettant de nous concentrer in fine sur deux plastifiants: la triacétine (TA), un plastifiant biosourcé fréquemment utilisé dans l'acétate de cellulose et le Diethyl Phthalate (DEP) qui est le plastifiant historique de l'acétate de cellulose et constitue une référence. Les propriétés mécaniques de l'acétate de cellulose plastifié obtenu par voie fondue étant peu étudiées dans la littérature, nous avons dans un premier temps évalué le comportement en traction et l'influence de différents paramètres tels que le taux et le choix du plastifiant mais également l'influence du procédé d'injection sur ces propriétés. Nous avons ainsi pu mettre en évidence l'apparition d'un régime de durcissement plastique (strain hardening en anglais) dès 8% de déformation sous certaines conditions. Il apparaît que le choix du plastifiant, la température d'analyse et la pré-orientation macroscopique des chaînes influencent significativement ce régime. Le durcissement plastique a déjà été observé dans d'autre polymères amorphes tels que le polycarbonate (PC) ou le poly(méthyle methacrylate) (PMMA) qui sont classés parmi les polymères amorphes dit « ductiles ». L'origine de ce régime est encore peu connue et suscite de nombreux débats, cependant il semblerait qu'il stabilise la déformation en évitant la localisation de l'endommagement et serait donc un paramètre clé pour l'amélioration de la ductilité de ces polymères. Afin de mieux comprendre cette ductilité nous avons réalisé des observations par microscopie électronique à balayage en transmission (STEM) ainsi que par diffusion des rayons X aux très petits angles (USAXS). Grâce à ces caractérisations nous avons pu décrire les micro-mécanismes d'endommagement sous traction de nos polymères depuis l'échelle macroscopique jusqu'à l'échelle nanométrique et ainsi décrire précisément les micro-mécanismes liés à l'initiation et la propagation de l'endommagement. Par ces analyses nous mettons en évidence la nucléation simultanée de craquelures nanométriques autour des défauts préexistants (liés au processus de mise en oeuvre). Ces craquelures vont ensuite croitre de façon très limitée jusqu'à atteindre la centaine de micron. Cependant lorsque la contrainte appliquée devient suffisamment élevée, une petite portion de ces craquelures vont se mettre à croitre plus rapidement jusqu'à entrainer la rupture de l'échantillon. Avec le DEP la cinétique de croissance est très rapide, entrainant une rupture brutale de l'échantillon dès qu'une craquelure atteint une dimension critique. Avec la TA néanmoins cette vitesse est plus lente, ce qui permet d'observer l'évolution d'une deuxième famille de craquelures. Ces travaux proposent un nouveau mécanisme d'endommagement dans l'acétate de cellulose plastifié basé sur des résultats expérimentaux et un modèle physique permettant une meilleure compréhension de la ductilité dans ces polymères

A combination of small- and ultra-small-angle X-ray scattering enabled the resolution of important intracellular constituents in Escherichia coli (ribosomes, DNA and proteins). The impact of treatment with three antibiotic agents was monitored., The application of small-angle X-ray scattering (SAXS) to whole Escherichia coli cells is challenging owing to the variety of internal constituents. To resolve their contributions, the outer shape was captured by ultra-small-angle X-ray scattering and combined with the internal structure resolved by SAXS. Building on these data, a model for the major structural components of E. coli was developed. It was possible to deduce information on the occupied volume, occurrence and average size of the most important intracellular constituents: ribosomes, DNA and proteins. E. coli was studied after treatment with three different antibiotic agents (chloramphenicol, tetracycline and rifampicin) and the impact on the intracellular constituents was monitored.

Cellulose acetate (CA) is a bio based polymer. Melt processing of cellulose based thermoplastic polymers is a real challenge. One problem is the existence of a narrow window between the melting point and the degradation temperatures for cellulose acetate with a substitution degree (DS) around 2.45 (which is developed and commercialized by Rhodia Acetow). As a consequence, its processing can only be considered with a sufficient amount of externalplasticizer (between 15 and 30% by weight). The corresponding polymer/plasticizer blends areamorphous and their mechanical properties are mainly governed by the presence of a high volume fraction of strong hydrogen bonds. The plasticization of cellulose acetate has been thesubject of many studies allowing us to focus on two plasticizers: triacetin (TA), an eco-friendlyplasticizer frequently used for cellulose acetate and diethyl phthalate (DEP) which is the historicplasticizer of cellulose acetate which constitutes a reference for this work as it is usually the case in the literature. Few studies have been published regarding the mechanical properties of bulk cellulose acetate (prepared via injection molding). It is described that they are comparable to those of PS or poly(methyl methacrylate) (PMMA) and have proven to be particularly interesting. Cellulose acetate based materials usually display a high Young modulus. But its small deformation at break limits its potential for new applications. The objectives of this thesis are to deeply understand the mechanical properties and damage mechanisms of bulk plasticized cellulose acetate polymers. For this purpose we first analyzed the tensile behavior and the influence of various parameters such as nature and content of the plasticizer, but also the influence of the injection process. We have thus been able to highlight the appearance of a strain hardening regime from 8% of deformation under certain conditions. It appears that the choice of the plasticizer, the temperature of the experiment and the macroscopic pre-orientation of the chains significantly influence this regime. Strain hardening has already been observed in other amorphous polymers such as polycarbonate (PC) or poly (methyl methacrylate) (PMMA) which are classified as amorphous polymers called "ductile". The origin of this regime is still undeveloped and much debated, however it appears that it stabilizes the deformation by avoiding the localization of damage and is therefore a key parameter for improving the ductility of these polymers. In order to better understand this ductility, we have made some analysis by Scanning Transmission Electron Microscopy (STEM) as well as Ultra Small Angles X-ray Scattering (USAXS). Thanks to these characterizations we have been able to describe the micromechanisms of damage from macro to nano-scales and thus precisely describe the micromechanisms related to initiation and propagation of damage. By these analyzes we highlight the simultaneous nucleation of nano crazes around pre-existing defects (related to the injection process). These crazes grow slowly until reaching the hundred microns. However, when the applied stress becomes sufficiently high, a small portion of these crazes starts to grow faster until the failure of the sample. With DEP the kinetics of growth is very fast, causing a brittle failure of the sample. With TA this growth is slower, which makes it possible to observe the evolution of the larger crazes. This work proposes a new mechanism of damage in plasticized cellulose acetate based on experimental results and physical interpretations, L'acétate de cellulose (CA) est un bio-polymère issu de la cellulose du bois. Sa température de dégradation (dont le degré de substitution 2,5 est développé et commercialisé par le Groupe Solvay) étant très proche de sa température de fusion, son procédé de mise en oeuvre par voie fondue ne peut être envisagé qu'avec l'ajout d'une quantité importante de plastifiant externe (entre 15 et 30% en poids). Le polymère plastifié obtenu est classé parmi les thermoplastiques amorphes et ses propriétés sont régies par un «réseau» de très fortes interactions polaires. La plastification de l'acétate de cellulose à fait l'objet de nombreux travaux nous permettant de nous concentrer in fine sur deux plastifiants: la triacétine (TA), un plastifiant biosourcé fréquemment utilisé dans l'acétate de cellulose et le Diethyl Phthalate (DEP) qui est le plastifiant historique de l'acétate de cellulose et constitue une référence. Les propriétés mécaniques de l'acétate de cellulose plastifié obtenu par voie fondue étant peu étudiées dans la littérature, nous avons dans un premier temps évalué le comportement en traction et l'influence de différents paramètres tels que le taux et le choix du plastifiant mais également l'influence du procédé d'injection sur ces propriétés. Nous avons ainsi pu mettre en évidence l'apparition d'un régime de durcissement plastique (strain hardening en anglais) dès 8% de déformation sous certaines conditions. Il apparaît que le choix du plastifiant, la température d'analyse et la pré-orientation macroscopique des chaînes influencent significativement ce régime. Le durcissement plastique a déjà été observé dans d'autre polymères amorphes tels que le polycarbonate (PC) ou le poly(méthyle methacrylate) (PMMA) qui sont classés parmi les polymères amorphes dit « ductiles ». L'origine de ce régime est encore peu connue et suscite de nombreux débats, cependant il semblerait qu'il stabilise la déformation en évitant la localisation de l'endommagement et serait donc un paramètre clé pour l'amélioration de la ductilité de ces polymères. Afin de mieux comprendre cette ductilité nous avons réalisé des observations par microscopie électronique à balayage en transmission (STEM) ainsi que par diffusion des rayons X aux très petits angles (USAXS). Grâce à ces caractérisations nous avons pu décrire les micro-mécanismes d'endommagement sous traction de nos polymères depuis l'échelle macroscopique jusqu'à l'échelle nanométrique et ainsi décrire précisément les micro-mécanismes liés à l'initiation et la propagation de l'endommagement. Par ces analyses nous mettons en évidence la nucléation simultanée de craquelures nanométriques autour des défauts préexistants (liés au processus de mise en oeuvre). Ces craquelures vont ensuite croitre de façon très limitée jusqu'à atteindre la centaine de micron. Cependant lorsque la contrainte appliquée devient suffisamment élevée, une petite portion de ces craquelures vont se mettre à croitre plus rapidement jusqu'à entrainer la rupture de l'échantillon. Avec le DEP la cinétique de croissance est très rapide, entrainant une rupture brutale de l'échantillon dès qu'une craquelure atteint une dimension critique. Avec la TA néanmoins cette vitesse est plus lente, ce qui permet d'observer l'évolution d'une deuxième famille de craquelures. Ces travaux proposent un nouveau mécanisme d'endommagement dans l'acétate de cellulose plastifié basé sur des résultats expérimentaux et un modèle physique permettant une meilleure compréhension de la ductilité dans ces polymères

The technical features and performance of a new instrument for time-resolved ultra-small-angle and coherent X-ray scattering are presented. The instrument enables static and kinetic investigations from ångström to micrometre size scales and time resolution down to the sub-millisecond range. Applications include elucidation of static and transient hierarchical structures in soft matter and biophysical systems., This article presents the main technical features and performance of the upgraded beamline ID02 at the ESRF. The beamline combines different small-angle X-ray scattering techniques in one unique instrument, enabling static and kinetic investigations from ångström to micrometre size scales and time resolution down to the sub-millisecond range. The main component of the instrument is an evacuated detector tube of length 34 m and diameter 2 m. Several different detectors are housed inside a motorized wagon that travels along a rail system, allowing an automated change of the sample–detector distance from about 1 to 31 m as well as selection of the desired detector. For optional combined wide-angle scattering measurements, a wide-angle detector is installed at the entrance cone of the tube. A scattering vector (of magnitude q) range of 0.002 ≤ q ≤ 50 nm−1 is covered with two sample–detector distances and a single-beam setting for an X-ray wavelength of 1 Å. In the high-resolution mode, two-dimensional ultra-small-angle X-ray scattering patterns down to q < 0.001 nm−1 can be recorded, and the resulting one-dimensional profiles have superior quality as compared to those measured with an optimized Bonse–Hart instrument. In the highest-resolution mode, the beam is nearly coherent, thereby permitting multispeckle ultra-small-angle X-ray photon correlation spectroscopy measurements. The main applications of the instrument include the elucidation of static and transient hierarchical structures, and nonequilibrium dynamics in soft matter and biophysical systems.

The feasibility for multi-speckle XPCS measurements in the ultra-low-angle range is demonstrated. The performance of the setup is illustrated by means of colloidal dynamics., Multi-speckle X-ray photon correlation spectroscopy (XPCS) measurements in the ultra-small-angle range are performed using a long pinhole collimation instrument in combination with two-dimensional photon-counting and high-sensitivity imaging detectors. The feasibility of the presented setup to measure dynamics on different time and length scales pertinent to colloidal systems is shown. This setup offers new research opportunities, such as for example in the investigation of non-equilibrium dynamics in optically opaque, complex systems over length scales from tens of nanometres to several micrometres. In addition, due to the short duration of the X-ray exposure involved in the ultra-small-angle range, possible radiation-induced effects are alleviated. Furthermore, the performance of two different detectors, a photon-counting Pilatus 300K and an integrating FReLoN CCD, are compared, and their applicability for accurate XPCS measurements is demonstrated.

This work of thesis deals with the micro-textural properties characterization of calcium oxide as CO2 capture solid sorbent, that strongly influence the carbonation reaction step performances. The investigation of the sorbent micro-structure was carried out by means of both in-situ and ex-situ techniques, varying the precursor (CaCO3) activation conditions and sintering effects on the final sorbent pore network. X-ray diffraction and N2-adsorption techniques were used to identify correlations between the sorbent micro-textural properties and the average sorbent crystallite size, by considering completely calcined calcium carbonate samples under vacuum conditions and varying the high temperature (800-900°C) heating step period. With the aim to investigate the high temperature and time dependent phenomena, as pore generation, sintering processes and pore closure, in-situ X-ray small angle scattering techniques were carried out for the first time to investigate the sorbent micro-structure evolution during calcite decomposition and the CaO carbonation reaction. Firstly, preliminary ex-situ measurements were performed at the Advanced Photon Source facilities of the Argonne National Laboratory to test the X-ray small angle scattering technique capabilities to investigate high porous samples, such as completely calcined CaCO3 and partially carbonated CaO-based sorbents, and successful results were obtained, providing a detailed quantitative description of the sorbent micro-structure. Therefore, for the first time in-situ time-resolved X-ray small angle scattering tests were carried out to investigate the sorbent micro-textural properties generation during the CaCO3 calcination reaction and their evolution during the CaO carbonation reaction. Two different sets of experiments were considered, by performing CaCO3 calcination reactions below 800°C in pure nitrogen and at high temperatures (800°C and 900°C) in presence of CO2 (from 1% up to 50% in balance with N2) in the reaction atmosphere. Afterwards, CaO carbonation tests were performed at 550°C with 0.5% of CO2 in balance with N2. Because of the non-catalytic gas-solid nature of the CaO carbonation reaction, a modified random pore model was proposed in order to represent both the reaction kinetics and the sorbent micro-structure evolution over the reaction. In addition, a computation fluid dynamic study on a thermo-gravimetric analyzer was performed to quantify the external mass transfer effects on the kinetics of the CaO carbonation reaction.

International audience; This article presents the main technical features and performance of the upgraded beamline ID02 at the ESRF. The beamline combines different small-angle X-ray scattering techniques in one unique instrument, enabling static and kinetic investigations from angstrom to micrometre size scales and time resolution down to the sub-millisecond range. The main component of the instrument is an evacuated detector tube of length 34m and diameter 2m. Several different detectors are housed inside a motorized wagon that travels along a rail system, allowing an automated change of the sample-detector distance from about 1 to 31m as well as selection of the desired detector. For optional combined wide-angle scattering measurements, a wide-angle detector is installed at the entrance cone of the tube. A scattering vector (of magnitude q) range of 0.002 q 50nm(-1) is covered with two sample-detector distances and a single-beam setting for an X-ray wavelength of 1 angstrom. In the high-resolution mode, two-dimensional ultra-small-angle X-ray scattering patterns down to q < 0.001nm(-1) can be recorded, and the resulting one-dimensional profiles have superior quality as compared to those measured with an optimized Bonse-Hart instrument. In the highest-resolution mode, the beam is nearly coherent, thereby permitting multispeckle ultra-small-angle X-ray photon correlation spectroscopy measurements. The main applications of the instrument include the elucidation of static and transient hierarchical structures, and nonequilibrium dynamics in soft matter and biophysical systems.

[EN] In order to improve understanding of the primary atomization process for diesel-like sprays, a collaborative experimental and computational study was focused on the near-nozzle spray structure for the Engine Combustion Network (ECN) Spray D single-hole injector. These results were presented at the 5th Workshop of the ECN in Detroit, Michigan. Application of x-ray diagnostics to the Spray D standard cold condition enabled quantification of distributions of mass, phase interfacial area, and droplet size in the near-nozzle region from 0.1 to 14 mm from the nozzle exit. Using these data, several modeling frameworks, from Lagrangian-Eulerian to Eulerian-Eulerian and from Reynolds-Averaged Navier-Stokes (RANS) to Direct Numerical Simulation (DNS), were assessed in their ability to capture and explain experimentally observed spray details. Due to its computational efficiency, the Lagrangian-Eulerian approach was able to provide spray predictions across a broad range of conditions. In general, this "engineering-level" simulation was able to reproduce the details of the droplet size distribution throughout the spray after calibration of the spray breakup model constants against the experimental data. Complementary to this approach, higher-fidelity modeling techniques were able to provide detailed insight into the experimental trends. For example, interface-capturing multiphase simulations were able to capture the experimentally observed bimodal behavior in the transverse interfacial area distributions in the near-nozzle region. Further analysis of the spray predictions suggests that peaks in the interfacial area distribution may coincide with regions of finely atomized droplets, whereas local minima may coincide with regions of continuous liquid structures. The results from this study highlight the potential of x-ray diagnostics to reveal salient details of the near-nozzle spray structure and to guide improvements to existing primary atomization modeling approaches.

International audience; Suspension plasma spraying (SPS) allows processing a stabilized suspension of nanometer-sized feedstock particles to form thick (from 20 to 100 μm, average values) deposits. The void content and porous network of such deposits are difficult to quantify (in terms of void and size distributions, anisotropy, etc.) using conventional techniques due to their low resolution. The combination of ultra-small-angle X-ray scattering (USAXS) and helium pycnometry permits to address some of the characteristics of this void network. Deposits of yttria-partially stabilized zirconia (YSZ) were manufactured by plasma spraying a suspension made of solid sub-micrometer-sized particles (50 and 400 nm) with several sets of spray operating parameters. Results indicate that the average void size exhibits the same scale as the solid structure; i.e., nanometer sizes and multimodal size distribution which varies with spray operating parameters. About 90% of voids (by number) exhibit characteristic dimensions smaller than 40 nm. The cumulative void volume fraction of such as-sprayed deposits varies between about 13 and 20%, depending upon operating parameters. The void network architecture evolves also with annealing conditions: the void size distribution evolves toward higher void characteristic dimensions as a result of sintering of smallest voids but the cumulative void content does not decrease significantly.

Electron-beam physical vapor deposited (EB-PVD) thermal barrier coatings (TBCs) display a lower thermal conductivity compared with the deposited bulk material. This effect is achieved due to the presence of pores within these films. The spatial and geometrical characteristics of the porosity influence directly the magnitude of the achieved reduction of the thermal conductivity. In this work, three EB-PVD coating containing different microstructures were manufactured by varying the manufacturing process parameters during the deposition process. Their corresponding thermal conductivities were measured via the laser flash analysis method (LFA) in both the as-coated state and after ageing (1100 °C/100 h). Analysis of the pore formation during processing was carried out by ultrasmall-angle X-ray scattering (USAXS). This technique is supported with a computer based modeling developed by researchers at Advanced Photon Source (APS) in ANL, USA, and in National Institute of Standards and Technology (NIST), USA. The model enables the characterization of the size, shape, volume and orientation of each of the pore populations in EB-PVD TBCs. The effect of these spatial and geometrical characteristics of the porosity on the thermal conductivity of the EB-PVD coatings were studied via a non-interacting approximation based on Maxwell's model. Results of LFA measurements and the applied approximation indicate an interrelation between the microstructure and the thermal properties of the analyzed EB-PVD coatings. Microstructures containing a higher volume fraction of fine anisotropic intra-columnar pores, and larger voids between feather-arms oriented at lower angles toward the substrate plane correspond to lower thermal conductivity values. Inter-columnar gaps do no significantly contribute to lowering the thermal conductivity due to their orientation parallel to the heat flux and their lower volume fraction compared with the volume occupied by the primary columns. On heat treatment, the deepest section of the gaps between feather-arms break-up into arrays of nano-sized low aspect ratio voids. The anisotropic, elongated intra-columnar pores evolve toward low aspect ratio shapes that are less effective in reducing the thermal conductivity.

6 pags., 9 figs., 2 tabs., The changes in the two axial long periods of injection moulded oriented linear polyethylene (PE) with a shish-kebab structure have been investigated as a function of temperature by ultra-small angle X-ray scattering (USAXS) using synchrotron radiation. The aim of the present study is to investigate the origin of both periodicities and to establish whether both scattering maxima are mutually related. The gradual transformation of the initial two long periods, L1 = 36.4 and L2 = 65.7 nm, measured at room temperature to the final single long period Lf = 120 nm at T = 130°C has been demonstrated on high molecular weight oriented PE samples. The detection of such high long periods (up to 150 nm for these samples) has been possible, for the first time, thanks to the use of the new high resolution USAXS beam line at the DORIS-bypass, DESY. On the other hand, low molecular weight PE shows, at room temperature, one long period corresponding to an oriented structure with a wide lamellar distribution. The coherently diffracting domains in the chain direction and the mean orientation of the lamellae derived from the azimuthal scanning of the SAXS profiles have also been examined as a function of temperature. The changes of the long period L1 with temperature are shown to be independent from the changes of the L2 periodicity. From the results it is concluded that the oriented shish-kebab structure, in the high molecular weight samples, consists of two separate populations of lamellar stacks with the layer normals parallel to the injection direction. During annealing only the thinner lamellae increase in thickness until they reach the size of the thicker ones at about T = 130°C. For higher temperatures than T = 137°C the scattering maxima vanish suggesting that the lamellae melt. Finally, after cooling from the melt the lamellae crystallize epitaxially on the preserved oriented shish fibrils and both stacking periodicities L1 and L2 appear again., The work was generously supported by CICYT, Spain (Grant PB94-0049). USAXS measurements at the DORIS-bypass, DESY, Hamburg, have been funded by the program Human Capital and Mobility, Access to Large Installations EC.

International audience; Focused X-ray beams for the study of heterogeneous samples have proven to be an essential tool for many scientific areas from materials science to soft matter, chemistry and nanotechnology. By combining X-rays with Raman spectroscopy in situ, samples can be studied at several size scales simultaneously, from molecular vibrations to structure and form factors, with high resolution in real space. By using such combined techniques within a microfluidics device, reactions can be probed at different stages as the reactants mix and flow through the device. Here we present the first use of a microfluidics device in a combined uSAXS – uRaman study. The formation and growth of silver nanoparticles, and their functionalisation with cysteamine, was monitored. The combination of such techniques and sample environments open new opportunities for studying materials at the nanoscale.

In titration experiments with NaOH, we have determined the full phase diagram of charged colloidal spheres in dependence on the particle density n, the particle effective charge Z(eff) and the concentration of screening electrolyte c using microscopy, light and ultrasmall angle x-ray scattering (USAXS). For sufficiently large n, the system crystallizes upon increasing Z(eff) at constant c and melts upon increasing c at only slightly altered Z(eff). In contrast to earlier work, equilibrium phase boundaries are consistent with a universal melting line prediction from computer simulation, if the elasticity effective charge is used. This charge accounts for both counterion condensation and many-body effects.